1. Field of the Invention
This invention relates to a card frame having a number of pairs of vertically spaced card guides for receiving cards (or also called boards) provided with plug connectors. Each pair of card guides is associated with a socket connector to establish electrical connection. A double-armed lever is pivotally mounted on each card by means of a pin at the lower front corner of the card and is adapted to be pivoted from out of an initial position, which is oblique to the forward edge of the card, into a latching position in an abutting relationship with the forward edge of the card. The short lever arm terminates in a hook and heel configuration. The hook portion is engageable with a receptacle fixed on the frame, as the card is inserted and the lever is pivoted upward into the latching position, with the hook bearing against the receptacle counter to the direction of insertion of the card. The heel portion bears against a front surface area of the frame as the lever is pushed downward into its initial position and the card is ejected by being levered outwards.
2. Description of the Prior Art
A card frame of the foregoing type is known from U.S. Pat. No. 4,083,616. The lever on the card serves to move the card into the fully plugged-in position, overcoming the insertion forces of the electrical connector whereby the insertion of the card is facilitated by the spaced bifurcated configuration of the lever while at the same time electrical connection is established. During the insertion movement, as the lever is moved upwardly, the hook on the lever bears against the fixed receptacle on the frame and the insertion forces, correspondingly translated, are transferred by the lever/pin assembly to the card. The situation is similar during the ejection of the card and the ensuing disconnection of the plug and socket connector. As the card is being withdrawn, the heel of the lever bears against the front portion of the frame and a correspondingly translated retraction force is transferred to the card as the lever is pivoted downward into the initial position.
In this known card frame, the fully plugged-in position of the card can be maintained only by resilient latching elements of the lever which exert a clamping action on each side of the card in the latched position of the lever. However, this clamping action can be overcome by applying an appropriate force to the card so that the card can be pulled out.
As is disclosed in U.S. Pat. No. 4,313,150, the latching position of the lever may be improved by a latching connection. To this end, however, the card must be provided with an aperture into which the projections of the lever may be snapped.